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Changes to flight software on 737 Max escaped FAA scrutiny
[NEW YORK] While it was designing its newest jet, Boeing decided to quadruple the power of an automated system that could push down the plane's nose - a movement that made it difficult for the pilots on two doomed flights to regain control.
The company also expanded the use of the software to activate in more situations, as it did erroneously in the two deadly crashes involving the plane, the 737 Max, in recent months.
None of those changes to the anti-stall system, known as MCAS, were fully examined by the Federal Aviation Administration.
Although officials were aware of the changes, the modifications didn't require a new safety review, according to three people with knowledge of the process. It wasn't necessary under FAA rules since the changes didn't affect what the agency considers an especially critical or risky phase of flight.
A new review would have required FAA officials to take a closer look at the system's effect on the overall safety of the plane, as well as to consider the potential consequences of a malfunction. Instead, the agency relied on an earlier assessment of the system, which was less powerful and activated in more limited circumstances.
Ever since the crashes - in Indonesia last October and Ethiopia last month - investigators, prosecutors and lawmakers have scrutinized what went wrong, from the design and certification to the training and response.
In both crashes, authorities suspect that faulty sensor data triggered the anti-stall system, revealing a single point of failure on the plane. Pilots weren't informed about the system until after the Lion Air crash in Indonesia, and even then, Boeing didn't fully explain or understand the risks. The FAA outsourced much of the certification to Boeing employees, creating a cozy relationship between the company and its regulator.
But the omission by the FAA exposes an embedded weakness in the approval process, providing new information about the failings that most likely contributed to the crashes in Indonesia and Ethiopia.
The FAA is supposed to be the gold standard in global aviation regulation, with the toughest and most stringent rules for certifying planes. But the miscalculation over MCAS undermines the government's oversight, raising further concerns about its ability to push back against the industry or root out design flaws.
While it is unclear which officials were involved in the review of the anti-stall system, they followed a set of bureaucratic procedures, rather than taking a proactive approach. The result is that officials didn't fully understand the risks of the more robust anti-stall system, which could cause a crash in less than a minute.
"The more we know, the more we realize what we don't know," said John Cox, an aviation safety consultant and former 737 pilot.
The FAA defended its certification process, saying it has consistently produced safe aircraft. An FAA spokesman said agency employees collectively spent more than 110,000 hours reviewing the Max, including 297 test flights.
The spokesman said FAA employees were following agency rules when they didn't review the change. "The change to MCAS didn't trigger an additional safety assessment because it did not affect the most critical phase of flight, considered to be higher cruise speeds," an agency spokesman said. "At lower speeds, greater control movements are often necessary."
A spokesman for Boeing said, "The FAA considered the final configuration and operating parameters of MCAS during Max certification, and concluded that it met all certification and regulatory requirements."
Some of the details of the evolving design of MCAS were earlier reported by The Seattle Times.
MCAS was created to help make the 737 Max handle like its predecessors, part of Boeing's strategy to get the plane done more quickly and cheaply.
The system was initially designed to engage only in rare circumstances, namely high-speed maneuvers, in order to make the plane handle more smoothly and predictably for pilots used to flying older 737s, according to two former Boeing employees who spoke on the condition of anonymity because of the open investigations.